Sometimes I wonder why Spawn is even a thing (and still rather popular!) currently, is it entirely on the cool design?
Spawn has followed a pattern.
It took a ton of criticism when he launched it so he got Alan Moore, Frank Miller, Dave Sim, and Neil Gaiman to write four issues with each taking one in Year One. In Year Two he had Grant Morrison write three issues and Gaiman, Moore, and Miller all did Spawn side projects. Alan Moore has done as much Spawn as anything else.
By Year Three McFarlane was back at the helm and the book was unreadable but looked pretty with his art. He started to have Capullo take over pencilling by Year Four.
This all took place over five or six years in the speculator boom with that helping the book. In addition, there were countless really good side books that Todd had little to nothing to do with.
Beginning around the collapse of the speculator boom the book actually got
much better. In the 00s Brian Holguin took over the book with Angel Medina doing the art. It was okay with highlights being the introduction of Nyx going for 50 issues. David Hine took over with highlight being the cool run by Brian Haberlin from 166 to 184.
He did it again after Hine's run with bringing in Whilce Portacio and Greg Capullo for a year. Pretty art, shit story. 185-200.
Then he takes a year and half off putting the thing on auto pilot before coming back full time as writer and cover artist. After that, Erik Larsen takes up art duties for a year.
By now I think the pattern is clear. The book will do something big every three to four years with Todd getting some big talent and shaking it up. That's what he did recently, coming back and getting Greg Capullo to draw the book. It's not right to say Spawn has surpassed Sim's Cerebus because McFarlane stopped doing meaningful artwork on the book back in the 90s! He's taking long stretches off. The bad of Spawn faaaarrrr outweighs the good.